Belt driven continuously variable transmission

ABSTRACT

This invention relates to a belt driven continuously variable transmission having a pressure regulating cam mechanism giving a pulley an axial force which corresponds to transmission torque and eliminates torque transmission by friction between a pressure regulating cam and a fixed race. The stationary sheave, whose outer surface is supported, with rotation free at a case, by a bearing and whose inner side encloses the pressure regulating cam mechanism, has a circular hub elongating axially to the back side of the stationary sheave. Therefore, torque from the engine is transmitted to the fixed race of the regulating cam mechanism through an input member, and further transmitted to the stationary sheave through a roller and a movable race of the regulating cam mechanism. Consequently, the stationary sheave is supported at the case by the bearing and the radial load does not work on the pressure regulating cam mechanism. Therefore, the axial force generated by the pressure regulating cam mechanism can be set to correspond to the torque from the engine side without getting any influence from the torque transmission by friction.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a belt driven continuously variabletransmission, especially relates to a belt driven continuously variabletransmission suitable for using in an automatic variable transmission tobe mounted on an automobile, in detail, relates to a pressure regulatingmechanism section generating an axle force corresponding to atransmission torque.

2. Description of Prior Art

Generally, A V-Belt type continuously variable transmission (CVT) has aprimary pulley and a secondary pulley each of which is made up of amovable sheave and a stationary sheave. Metallic belt is wound aroundboth of these pulleys. A shifting operation is done at a required momentby moving the movable sheave with a hydraulic pressure piston.

Therefore, the continuously variable transmission, where a hydraulicpressure is used, needs an oil pump and a hydraulic pressure passage.This structure makes the device not only large and complicated but alsounfavorable for the transmission efficiency and the belt endurancebecause the structure generates the pressing force more than needed,which furthermore, makes it impossible to transmit, as the belt pressingforce becomes short in supply, when the hydraulic pressure decreases bysome reasons.

The applicant of the present invention has proposed a belt drivencontinuously variable transmission 30', as shown in FIG. 5, to wind ametallic belt 33 around a primary pulley 31 and a secondary pulley 32,whose movable sheave 31b and 32b are moved axially by actuatormechanisms 35 and 36 such as ball thread mechanism, and to arrange apressure regulating cam mechanism 34' giving an axial force whichcorresponds to a transmission torque to a primary sheave 31a. (refer tothe Japanese Laid Open Patent No.62-13853)

In the belt driven continuously variable transmission 30', both thesheaves 31a and 31b of the primary pulley 31 are supported on theprimary shaft 30b, the pressure regulating cam mechanism 34' issupported on a boss section `a` of a stationary sheave 31a and alsosupported on a case by a bearing 1'.

Therefore, in the continuously variable transmission 30', a torque fromthe primary shaft 30b is transmitted to the stationary sheave 31athrough the pressure regulating cam mechanism 34' and also transmittedfrom the primary pulley 31 to the secondary pulley 32 through a belt 33.When the torque is transmitted form the pressure regulating cammechanism 34' to the stationary sheave 31b, not only a torque to betransmitted through the pressure regulating cam mechanism 34', or afixed-side race 34'a, a roller 34'b and a movable-side race 34'c, butalso another torque to be transmitted directly by the friction of thefixed-side race 34'a and a stationary sheave 31a, is produced.

A torque made by the friction varies largely because the pulley 31 issupported through the pressure regulating cam mechanism 34', so that theradial force between the sheave 31a and the boss section `a` altersaccording to the belt tension. For example, generally, supporting theratio of the whole torque to be transmitted is (ten), the ratio of atorque transmitted through the fixed-side race 34'a, a roller 34'b and amovable-side race 34'c (eight) and the ratio of a torque transmitted bythe frictional force between the fixed-side race 34'a and the fixed-sidesheave 31a (two), the ratio of the frictional force torque can beincreased from (two) to around (five) by the variation of the belttension. Therefore, the transmission torque through the pressureregulating cam mechanism 34' also varies, so that the pressing forceworking on the belt 33 is made uneven. To overcome this unevenessrequires a pressure regulating cam mechanism which generates a largeaxial force in order to keep a certain pressing force, which lowers theendurance and the transmission efficiency of the V-belt 33.

This invention is purposed to provide a belt driven continuouslyvariable transmission which transmits whole torque through a regulatingcam mechanism so that the belt pressing force which responds correctlyto the transmission torque can be obtained.

SUMMARY OF THE INVENTION

This invention is proclaimed in order to solve above problems. Forexample, as shown in FIG. 1, this invention has a primary pulley (31)and a secondary pulley (32) both of which are supported respectively bya shaft (30b) and (30a), and both of which are composed of two sheaves(31a), (31b), (32a) and (32b), all relatively movable to the axialdirection, and this invention is a belt driven continuously variabletransmission (30) winding a belt (33) around the pulleys (31) and (32).This belt driven continuously variable transmission (30) has a pressureregulating mechanism (34), such as a cam mechanism, giving an axialforce corresponding to the transmission torque to at least one of thepulleys (31) and (32), and also has actuator mechanisms (35) and (36)such as a ball thread mechanism moving movable sheaves (31b) and (32b)of both the pulleys axially.

The pressure regulating mechanism (34) is arranged right above thetransmitting path of a sheave (31a) giving an axial force in order toeliminate the supporting relation to the radial direction of the sheave(31a) which is supported directly in the case (15) by a bearing (1) and(5a).

To put it concretely, the sleeve where the axial force is given has acircular hub (2) elongating axially from the back side of the sheave(31a). The outer surface of the hub (2) is supported with rotation freeat the case (15) by the bearing (1) and the pressure regulatingmechanism (34) is arranged in the inner surface of the hub (2).

With the above structure, the rotation of the input member (90C) istransmitted to the fixed side race (34a) of the pressure regulatingmechanism (34) and the fixed sheave (31a) of the primary pulley (31)through the pressure regulating mechanism (34). At this process, thefixed sheave (31a) is supported to the case (15) by the bearing (1). Asthe radial force does not work on the pressure regulating mechanism(34), the whole torque of the input member (90C) is transmitted throughthe pressure regulating mechanism (34). So an axial force (S)corresponding to the transmission torque works on the sheave (31a) andholds the belt (33) with suitable force. And the torque transmitted tothe primary pulley (31) is transmitted to the secondary pulley (32)through the belt (33) where the suitable force works.

As has been explained, by this invention, the whole transmission torquefrom the input member (90C) is transmitted to the pulley (31) throughthe pressure regulating mechanism (34), so the axial force (S)corresponding correctly to the transmission torque works on the pulley(31) and the adequate belt holding force can be obtained. The axialforce generated at the pressure regulating mechanism (34) can be setsmall in order to correspond to the transmission torque, which canenhance the belt endurance and can improve the transmission efficiency.As the sheave (31a) is supported directly at the case (15) by thebearings (1) and (5a), the supporting precision of the pulley (31) isimproved and the vibration and the noise of the belt (33) is reduced sothat the reliability of the belt driven continuously variabletransmission (30) can be ensured.

Incidentally, the reference numerals in the prentheses are used only forreference with the drawings and do not define the invention. The samenumber may be named differently in the following description and in theprevious description in which broader concepts are adopted.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a cross sectional view of a belt driven continuously variabletransmission relating to this invention;

FIG. 2 is a schematic representation of a continuously variabletransmission where this invention is applicable;

FIG. 3 is a table of the operation of each elements;

FIG. 4 is a cross sectional view of the contiguously variabletransmission;

FIG. 5 is a cross sectional view of the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A detailed description of the preferred embodiments shall now be shownwith the drawings.

This automatic continuously variable transmission 12, as shown in FIG.2, has a single planetary gear device 20, a belt driven continuouslyvariable transmission 30, a transfer device 80, an input shaft 60, anoutput member 70 composed of a reduction gear device 71 and adifferential device 72, a fluid coupling 13 having a lock-up clutch CLand a forward/reverse switching device 90 composed of a dual planetarygear device. And in the single planetary gear device 20, an element 20S(or 20R) are to be a reaction force supporting member when using thesingle planetary gear device 20 as a reduction mechanism, and theelement 20S (or 20R) moves together with a restraining means F and B1through a transfer device 80 and can connect/disconnect with the inputshaft 60 through a high clutch C2.

To put it concretely, a ring gear 20R of the planetary gear device 20moves together with a secondary shaft 30a of a continuously transmission30, a carrier 20C moves together with the output member 70, and the sungear 20S moves together with a low one-way clutch F and a low coast &reverse brake B1 both composing an engaging means through the transferdevice 80 and also moves together with a high clutch C2.

In the dual planetary gear device 90, the sun gear 90S connects to andinput shaft 60, the carrier 90c connects to both a primary shaft 30b ofthe continuously variable transmission 30 and an input shaft 60 througha forward clutch C1 and a ring gear 90R connects to a reverse brake B2.

Based on the above structure, each clutches, brakes and one-way clutcheswithin the automatic continuously variable transmission 12 operate asshown in FIG. 3. shows that the lock-up clutch CL can move at a requiredmoment.

In detail, at the low speed side L of D range, a forward clutch C1connects and a low one-way clutch F operates. At this stage, therotation of the engine crank shaft is transmitted to the input shaft 60through the lock-up clutch CL or the fluid coupling 13, to the sun gear90S of the dual planetary gear device 90 directly and to the carrier 90Cthrough the forward clutch C1. Therefore, the dual planetary gearmechanism 90 rotates together with the input shaft 60, transmits thepositive rotation to the primary shaft 30b of the belt drivencontinuously variable transmission 30. Furthermore, the rotation shiftedat a required moment in the continuously variable transmission 30 istransmitted from the secondary shaft 30a to the ring gear 20R of thesingle planetary gear device 20. While, at this state, the sun gear 20Swhich is the reaction force supporting element to receive the reactionforce is stopped by a low one-way clutch F through a transfer device 80.Therefore the rotation of the ring gear 20R is taken out from thecarrier 20C as reducing rotation, and transmitted to the axle 73 throughthe reduction gear device 71 and the differential device 72.

At the high speed side H of D range, not only the forward clutch C1 butalso a high clutch C2 connects. At this state, the positive rotationshifted at a required moment in the continuously variable transmissionis taken out from the secondary shaft 30a and input into the ring gear20R of the single planetary gear device 20. While, at the same time, therotation of the input shaft 60 is transmitted to the sun gear 20S of thesingle planetary gear device 20 through the high clutch C2 and thetransfer device 80. By this process, torque of the ring gear 20R and thesun gear 20S is combined and taken out from the carrier 20C. At thisstate, as the rotation against the reaction force through the transferdevice 80 is transmitted to the sun gear 20S, the torque loop does notoccur and the certain positive torque is transmitted through thetransfer device 80. The combined torque from the carrier 20C istransmitted to the axle shaft 73 through the reduction gear device 71and the differential device 72.

At the operation of D range, the rotation is free at the reverse torqueoperation (at the engine brake) based on the one-way clutch F, while atthe operation of S range, besides the low one-way clutch F the low coast& reverse brake B1 operates and power can be transmitted even at thereverse operation.

At the R range; the reverse brake B2 operates together with the lowcoast & reverse brake B1. At this state, the rotation of the input shaft60 is input to the belt driven continuously variable transmission 30 asa reverse rotation from the carrier 90C as the ring gear 90R is fixed atthe dual planetary gear device 90. While, based on the operation of thelow coast & reverse brake B1, the sun gear 20S of the single planetarygear device 20 is fixed so that the reverse rotation of the belt drivencontinuously variable transmission 30 is decelerated at the planetarygear device 20 and taken out to the output member 70.

And at P range and N range, the low coast & reverse brake B1 operates.

The embodiment of the automatic continuously variable transmission willbe explained along with FIG. 4.

This continuously variable transmission 12 has a transmission case 15where an input shaft 60 and a primary shaft 30b of the continuouslyvariable transmission 30 are supported on the same shaft with rotationfree and composes a first shaft. A secondary shaft 30a of thecontinuously variable transmission 30 and the gear shaft 70a aresupported on the same shaft with rotation free and composes a secondaryshaft. Furthermore, on the primary shaft, arranged, a fluid coupling 13having a lock-up clutch CL, a forward clutch C1, a high clutch C2, a lowcoast & reverse brake B1, a reverse brake B2, a controlling section 40having a low one-way clutch F, a dual planetary gear device 90 composinga forward/reverse switching device and a hydraulic pressure pump 17. Onthe secondary shaft, a single planetary gear device 20 is arranged.

Furthermore, to explain the controlling section 40 and the inputsection, at the input shaft 60, whose one side edge engages with thelock-up clutch CL and the output member of the fluid coupling 13, andwhose the other side edge engages with the sun gear 90S of the dualplanetary gear device 90. On the input shaft 60 a sleeve section 15awhich is fixed on the case 15 is arranged. To the sleeve section 15a, asprocket 81 is connected through the one-way clutch F, while a sleeveshaft 41 connecting to the input shaft 60 is supported with rotationfree. Furthermore, at one side of a flange section 41a extruding fromthe sleeve shaft 41, the forward clutch C1 is arranged together with ahydraulic actuator 42, and at the other side, a high clutch C2 isarranged together with a hydraulic actuator 43. The operated-side of thehigh clutch C2 is connected to the boss section of the sprocket 81, andthe boss section 81 is connected to the low coast & reverse brake B1arranged together with the hydraulic actuator 45 in the case 15. Theoperated-side of the forward clutch C1 is connected to the carrier 90Cof the dual planetary gear device 90 whose ring gear 90R engages withthe reverse brake B2 arranged in the case 15 together with the hydraulicactuator 46 (refer to FIG. 2). Here, the carrier 90C supports a pinion90Pl engaging with the sun gear 90S and a pinion 90P2 engaging with thering gear 90R, and the pinions 90Pl and 90P2 mesh with each other.

The single planetary gear device 20 is situated on the gear shaft(output shaft) 70a composing the secondary shaft, the ring gear 20Rconnects to the flange section `q` integrally arranged on the primaryshaft 30a of the belt driven continuously variable transmission 30 to beexplained later on. On the gear shaft 70a, a sprocket 82 is supportedwith rotation free together with the sun gear 20S. On the gear shaft70a, the carrier 20C supporting the pinion 20P with rotation free isspline-coupled.

While, between the sprocket 82 integrally composed with the sun gear 20Sand the sprocket 81 supported by the low one-way clutch F, a silentchain 83 is set round and composes the transfer device 80 by thesesprockets and the chain.

The gear shaft 70a composes the output member 70 integrally composing agear 71a, which engages with a gear 71c fixed to an intermediate shaft71b. Furthermore, on the intermediate shaft 71b, a small gear 71d isarranged. The small gear 71d engages with the ring gear 72a fixed on thedifferential device 72 and composes a reduction device 71. A right/leftfront axle shaft 73l and 73r elongate from the differential device 72.

The belt driven continuously variable transmission 30 related to thisinvention, as shown in FIG. 1, is arranged with a primary pulley 31, asecondary pulley 32 and a belt 33 set around both of these pulleys,which are made of stationary sheave 31a, 32a and movable sheave 31b,32b.

The stationary sheave 31a of the primary pulley 31 encloses the primaryshaft 30b and has a long boss section `b` elongated to the side of themovable sheave 31b. A cylinder-shaped hub 2 is integrally composed onthe back surface of the flange section `d`. The outer diameter surfaceof the hub 2, whose inner diameter side has a pressure regulating cammechanism 34 arranged, is supported by a case 15 with rotation freethrough a roller bearing 1.

The pressure regulating cam mechanism 34 is composed of a fixed race 34aand a movable race 34c, both of which have waveshaped edge surfaces anda roller 34b interposed between both edges. While, the fixed race 34a isspline-coupled with the edge of the primary shaft 30b and stopped bysnap rings, etc. The movable race 34c connects to a spline 2a arrangedon the inner diameter surface of the hub section 2 with axial directionmovement free. Between the fixed race 34a and the inner diameter surfaceof the hub section 2 a certain interval `c` is arranged. Between themovable race 34c and the primary shaft 30b a certain interval `c` isalso arranged. Therefore between the fixed race 34a and the stationarysheave 31a, and, the movable race 34c and the shaft 30b, no torquetransmission by frictional contact occurs. On the outer diameter surfaceof the fixed race 34a where the carrier 90C, or the input member, of thedual planetary gear 90, a spline is arranged. The movable race 34ctransmits the torque to the fixed sheave 31a through the spline 2a, andprovides the axial force S which is in proportion to the transmittingtorque through many disc springs 38 which are arranged in the concavesection of the stationary sheave 31a, and the disc springs provide thepreload.

While, an oil passage `g` whose edge is pluged by a cap `f` runs throughright in the middle of the primary shaft 30b where many holes applyinglubricating oil to required places are arranged. The edge of the dualplanetary gear device 90 is an "in-low" section `h` engaging with theinput shaft 60. The outer diameter surface of the edge is a splinesection `i` and the section where engages with the boss section `b` ofthe stationary sheave 31a is an oil groove `j`. And one of the ends ofthe shaft 30b, which holds aloof from the gear device 90, enlarges toshape integrally a large diameter flange section `k`, whosecircumferential side of the inner surface constitutes a retainer surfacefor a thrust bearing 3a. While, on the case 15 a cap 15a is fixed by abolt B covering the large diameter flange `k`. The shoulder section 15bof the case 15 supports the regulating retainer 4.

The regulating retainer 4 is made of circular member having channelshaped cross section. An inner diameter brim 4a supports the stationarysheave 31a with rotation free through the radial roller bearing 5a. Aspline `m` is arranged on the outer surface of the brim 4a. A thrustbearing 3a is supported by the outside of the side wall section 4b. Anworm wheel 4c is arranged on the outer brim section of the regulatingretainer. This worm wheel 4c has a worm 4d engaged and rotates theregulating retainer 4. By rotating the worm 4d, the regulating retainer4 rotates at an unvariable position in axial direction with touching thebearing 3a.

While, at the movable sheave 31b the boss section `n` is supported bythe boss section `b` of the stationary sheave 31a with only slidingmovement free through the ball spline 6a, and a ball thread device 35 isarranged on the back section of the flange section `o`. The ball threaddevice 35 is made of a bolt section 35a and a nut section 35b. On theinner surface of the bolt section 35a, a groove to engage with thespline `m` of the regulating retainer 4 is arranged. On the outerdiameter surface of the nut section 35b a spline `e` is arranged. Acircular gear section 35c whose outer diameter section has aspiral-circular gear is spline-coupled to the outer diameter surface ofthe nut section 35b. Between the gear section 35c and the flange section`o` of the movable sheave 31b, a thrust bearing 3b is arranged.Therefore, a bolt section 35a of a ball thread device 35 is connected tothe case 15, without rotation free, through the regulating retainer 4,and the section 35a is connected to the primary shaft 30b, without axialmove, through the thrust bearing 3a. The nut section 35b of the ballthread device 35 is connected to the movable sheave 31b with beingaxially movable through the thrust bearing 3b.

While, the secondary pulley 32 has a stationary sheave 32a and a movablesheave 32b. The stationary sheave 32a is supported in the case 15, withrotation free, through a roller bearing 5b, and the sheave 32a isconnected to a secondary shaft 30b, without rotation, through a key 6c.The movable sheave 32b is supported, with only axial movement allowed,by the secondary shaft 30a through a ball spline 6b.

The oil passage g' is running through the middle of the secondary shaft30a and has the edge pluged by a cap f'. Many side holes to supplylubricating oil to required places are also arranged at the secondaryshaft 30a, whose end section namely the side of the single planetarygear device 20 enlarges to be a large diameter flange section `q`. Thediameter of the oil passage g' becomes stair-shapedlly large,corresponding to the flange section q'. The stair-shapedlly enlargedsection encloses the output shaft 70a through a needle bearing 5c. Onthe surface of the shaft 30a, starting from the large diameter flangesection `q`, a ball groove `r`, a key groove `s` and a thread `t` arearranged and each groove supports the movable sheaeve 32b and thestationary sheaeve 32a, and a nut member 9 is screwed to the thread `t`

A regulating ring 7 is fixed by a bolt B on the approxiamately samevertical plane with the bearing 5c of the case 15. Furthermore, aregulating retainer 8 is directly supported by a shoulder section madein the case 15. The regulating retainer 8 whose cross section is channelshape is made of a circular member. An inner brim section 8a of theretainer 8 supports the secondary shaft 30a with rotation free throughthe roller bearing 5d, and outer diameter surface of the brim 8aarranges a spline `u`. Furthermore, between the outside of a side wallsection 8b and the flange `q`, a thrust bearing 3c is held. Thecircumference of the retainer 8 has threads 8c to engage with the thread7a of the ring 7.

Furthermore, on the back side surface of a flange section `y` of themovable sheaeve 32b, a ball thread device 36 which is composed of a boltsection 36a and a nut section 36b is arranged. A groove to mate with thespline `u` of the regulating retainer 8 is arranged on a part of theinner side of the bolt section 36a. The outer surface of the nut section36b has a spline `x`. A noncircular gear section 36c where anon-circular gear is formed on the circumference is coupled to thespline `x`. Between the gear section 36c and the flange section `y`, athrust bearing 3d is disposed. Therefore the bolt section 36a of theball thread device 36 is connected to the case 15 without rotationthrough the ring 7 and the retainer 8, and the bolt section 36a is alsoconnected to the flange `q` without axial move through the thrustbearing 3c. The nut section 36b is connected to the movable sheaeve 32bthrough the thrust bearing 3d so that the nut section 36b moves axially.

A shifting device 100 regulating the distance between the primary pulley31 and the secondary pulley 32 is disposed between two pulleys 31 and 32so that the device 100, the primary shaft 30b and the secondary shaft30a become apexes of triangle in cross sectional view. The shiftingdevice 100, as shown in FIG. 4, has an operating shaft 101 supported bythe case 15 with rotation free. As FIG. 4 is an exploded view, theoperating shaft 101 is drawn at the upper part, however, practically,the operating shaft 101 is placed between the primary shaft 30b and thesecondary shaft 30a when seen from the same position where FIG. 4 isdepicted. At the operating shaft 101, a circular gear 102 and anon-circular gear 103 are fixed. The circular gear 102 engages with acircular gear 35c fixed to the nut section 35b at the side of theprimary pulley 31. The non-circular gear 103 engages with thenon-circular gear 36c fixed to the nut section 36b at the side of thesecondary pulley 32. The circular gear 102 meshes with a small gear 105amade of a spur gear or a herical gear formed on the intermediate shaft105 which is disposed at opposite side of the circular gear 35c. A largegear 105b is formed on the intermediate shaft 105, the gear 105b mesheswith a small gear 106a formed on an intermediate shaft 106. These gearscompose a reduction device 107 which has a good efficiency oftransmission. A comparatively small electric motor (or a supersonicmotor) 109 is disposed with its one side coming out from the case 15. Onan output shaft 109a of the motor 109, a shaft 110 having a smalldiameter gear 110a which engages to the large diameter gear 106b formedon the intermediate shaft 106 is fixed. A brake disc 111a is fixed onthe shaft 110. An electromagnetic coil member 111b is fixed by a bolt atthe case 15. The electromagnetic coil member 111b and the brake disc111a compose an electromagnetic brake 111 which keeps the operatingshaft 101 at suspending condition. As the supersonic motor has asupporting mechanism inside, when it is used, no special supportingmechanism such as the electromagnetic brake is required.

A assembly of the belt driven continuously variable transmission 30shall be explained in detail.

At the primary side, the thrust bearing 3a is arranged on the primaryshaft 30b and the stationary sheave 31a, the movable sheaeve 31b, thethrust bearing 3b and a ball thread device 35 both of which are inassembled manner, and a regulating retainer 4, are assembled on theshaft 30b. Then a disc spring 38, the movable race 34c and the roller34b are enclosed in the hub section 2 and the fixed race 34a is screwedto the thread `i` and stopped, which completes the whole assembly. Atthe secondary side, from the thread `t` side, the thrust bearing 3c, theregulating retainer 8, the ball thread device 36, the movable sheave 32band the stationary sheave 32a, are assembled in this order. The nutmember 9 is screwed to the thread `t`, which completes the wholeassembly.

A sub assembly at the primary side, composed as the above explanation,arranges a belt 33 between both the sheaves 31a and 31b, inserts a hug 2of the stationary sheave into a roller bearing 1 and inserts theregulating retainer 4 into the shoulder 15b of the case 15 which isseparatable into two parts. A sub assembley at the secondary side, whoseregulating retainer 8 is interposed in the shoulder of the case 15,whose boss section of the movable sheave 32b is interposed in the rollerbearing 5b, is arranged in the two-separable case 15.

At this state, by the tolerances among each member the initial belttension is not correct, and the stroke at the transmission torquereversal of the regulating cam mechanism is big. So at the secondaryside, the regulating retainer 8 is rotated by required amount, the boltsection 36a integral with the retainer 8 is rotated against the nutsection 36b and the distance of the pulley 32 is regulated. Then, thegear 7a of the regulating ring 7 meshes with the gear 8c of the retainer8 and the ring 7 is fixed by the bolt B. While, at the primary side, anwarm 4d is rotated to rotate the regulating retainer 4. The bolt section35a rotates together with the retainer 4. As the bolt section 35a is setaxially by the thrust bearing 3a, the nut section 35b moves axially toregulate the distance of the pulley 31 correctly. By this process, theinitial belt tension is regulated to make the stroke of the pressureregulating cam mechanism 34 correct and the axial position of bothpulleys 31 and 32, namely, the belt driving line is regulated to becorrect.

If an warm 4d is operated from outside the case 15, regulating operationcan be done even after the case is composed. And the warm 4d can bearranged at the secondary side or at both the secondary side and theprimary side. The regulating retainer can be arranged only either theprimary or the secondary side.

The operation of this embodiment shall be explained below.

The rotation of the engine crank shaft is transmitted to the input shaft60 through the lick-up clutch CL or the fluid coupling 13 and thentransmitted to the sun gear 90S of the dual planetary gear device 90 andto the sleeve shaft 41. At the D range and the S range, the forwardclutch C1 connects and the reverse brake B2 releases, so that at thedual planetary gear device 90, the sun gear 90S and the carrier 90Crotate together and the positive rotation is transmitted from thecarrier 90C to the fixed race 34a of the pressure regulating cammechanism 34 at the belt driven continuously variable transmission 30.

The rotation of the fixed race 34a rotates the primary shaft 30bengaging with the thread `i` and also rotates the stationary sheave 31aof the primary pulley 31 through the roller 34b arranged on thewave-shaped surface, the movable race 34c and the spline 2a andfurthermore rotates the movable sheave 31b through the ball spline 6a.At this state, the both sides of the stationary sheave 31a are supportedby the case 15 through the bearing 1 and 5a. As the interval `c` is madebetween the fixed race 34a and the section 2 and also between themovable race 34c and the primary shaft 30b, the torque is nottransmitted from the fixed race 34a and from the primary shaft 30b tothe stationary sheave 31a by the friction. The whole torque transmittedfrom the carrier (the input member) 90C is transmitted to the stationarysheave 31a through the pressure regulating cam mechanism 34. And at thepressure regulating cam mechanism 34, the axial force corresponding tothe input torque which operates on the fixed race 34a operates on theback surface of the sheave 31a through the disc springs 38. While, atthe other sheeve 31b, the ball thread mechanism 35 is fixed in axialdirection to correspond to a certain shift ratio, therefore the reactionforce having as same strength as that of worked on the backside of thesheave 31a through the thrust bearing 3b. By this process, the primarypulley 31 holds the belt 33 by the holding force corresponding to theinput torque. The axial force S working on the movable sheave 31b workson the large diameter flange section `k` of the primary shaft 31bthrough the thrust bearing 3b, the ball thread device 35, the regulatingretainer 4 and the thrust bearing 3a. The axial force S working on thestationary sheave 31a works from the fixed race 34a to the shaft 30bthrough the thread `i`. So the axial force S is kept inside the shaft30b as a tension force. Furthermore, the rotation of the belt 33 istransmitted to the secondary pulley 32, then to the secondary shaft 30athrough the key 6c and the ball spline 6b.

At the belt transmission, the motor 109 is controlled based on thesignals from each sensors such as the opening ratio of the throttle andthe vehicle speed. The operating shaft 101 is rotated through thereduction device 107. Then the nut section 35b of the ball thread device35 at the side of the primary pulley 31 is rotated through the circulargears 102 and 35c. The nut section 36b of the ball thread device 36 atthe side of the secondary pulley 32 is rotated through the non-circulargears 103 and 36c. By this process, the nut sections 35b and 36b rotaterelatively between the bolt section 35a and 36a which are fixed on thecase 15 by the regulating retainer 4 and 8. The ball thread devices 35and 36 move the movable sheaves 31b and 32b through the thrust bearings3b and 3d and the primary pulley 31 and the secondary pulley 32 are setwith certain effective diameter, and the predetermined torque ratio canbe obtained. The electric currency is cut, when the torque ratio reachesthe predetermined level, and the electromagnetic brake 111 startsoperating and keeps both the pulleys 31 and 32 at the same torque ratio.At this state, both the ball thread devices move linearly. Therefore thedifference of traveling distances between the movable sheaves originallypredetermined by the belt 33 and the the ball thread mechanisms arises,however, the side of the secondary pulley 32 rotates throughnon-circular gears 103 and 36c, the movable sheaves are moved accordingto the original distance of traveling. The belt holding force by boththe sheaves 31a, 31b and 32a, 32b works, at the primary 31 side, to pullthe primary shaft 30b through the thrust bearing without working on thecase 15. At the secondary pulley 32 side, the belt holding force workingto pull the secondary shaft 30a without working on the case 15.

Furthermore, the rotation of the secondary shaft 30a of the belt drivencontinuously variable transmission 30 is transmitted to the ring gear20R of the single planetary gear device and also to the gear shaft 70athrough the carrier 20C.

And at the low-speed side L of D range, as shown in FIG. 3, as the lowone-way clutch F is in operating condition, a sun gear 20S receives thereaction force when the torque transmission from the ring gear 20R tothe carrier 20C. The rotation of this sun gear 20S is stopped by the lowone-way clutch F through a transfer device 80. The single planetary geardevice 20 composes and serves as reduction mechanism. Therefore, therotation of the secondary shaft 30a of the belt driven continuouslyvariable transmission 30 is only reduced first at the single planetarygear device 20 then through a reduction gear device 71 having the gear71a, 71c, the middle shaft 71b, the gear 71d and the mount gear 72a andfinally transmitted to right and left front axle shaft 73l and 73rthrough the differential device 72.

When the opening ratio and the vehicle speed reach certain levels, ahigh clutch C2 receives signals from the controlling unit in order toconnect and get switched to the high-speed side. The rotation of theinput shaft 60 is first transmitted to the belt driven continuouslyvariable transmission 30, then through the sleeve shaft 41 and the highclutch C2 transmitted to the sprocket 81 and finally to the sun gear 20Sof the single planetary gear device 20 through the silent chain 83 andthe sprocket 82. In this process, as the sprocket 81 at the input sideof the transfer device 80 receives the reaction force from the sun gear20S of the single planetary gear device by the low one-way clutch F, ashift-shock caused by the gear changes is prevented, the rotation startssmoothly by the connection of the high clutch C2 and the torque istransmitted to the sun gear 20S. By this process, the torquecontinuously transmitted by the belt driven continuously variabletransmission and the torque through the transfer device 80 are combinedat the single planetary gear device 20 and the combined torque istransmitted from the carrier 20C to the gear shaft 70a. Furthermore, asthe same as the low-speed side, the combined torque is transmitted tothe right and left front axle shafts 73l and 73r through the reductiongear device 71 and the differential device 72.

As the low-speed side L of S range receives a negative torque made bythe engine brake and so on, the low-coast & reverse brake B1 engages andboth the forward and the reverse rotations of the sprocket 81 isstopped. The condition of the high-speed side H at S range is as thesame with that of the high-speed side of D range.

While, at the R range, the forward clutch C1 is released and the reversebrake B2 is engaged. Therefore, the rotation of the input shaft 60transmitted to the sun gear 90S of the dual planetary gear device 90 istransmitted as a reverse rotation, due to the suspension of the ringgear 90R, from the carrier 90C to the primary shaft 30b of the beltdriven continuously variable transmission 30. At this process, thereaction torque from the sun gear 20S through the transfer device 80works on the sprocket 81 as the reverse rotation, the low-coast &reverse brake B1 operates and the sprocket 81 is stopped.

FEASIBILITY OF THE RELATED INDUSTRIES

As has been explained up to now, the belt driven continuously variabletransmission having a pressure regulating mechanism giving a shaft forcecorresponding to the transmission torque relating to this invention canbe used in any power transmitting device for transportation uses andindustrial uses, and especially best used in automatic continuouslyvariable transmission carried on automobiles.

We claim:
 1. A belt driven continuously variable transmission includinga primary pulley and a secondary pulley both of which being made of tworelatively slidable sheaves being supported by shafts, a pressureregulating mechanism giving an axial force according to the transmissiontorque to at least one of said pulleys, an actuator mechanism to movemovable sheaves of both pulleys axially, a belt wound around bothpulleys, improvement comprising;said pressure regulating mechanism whichis situated right in front of a power transmission path led to a sheaveimparting axial force so that said sheave and said pressure regulatingmechanism have no radial interconnection of supporting, said sheaveimparting axial force which is directly supported on a case through abearing.
 2. A belt driven continuously variable transmission defined inclaim 1, wherein a sheave which axial force is given has a tubular hubsection elongated toward axial direction, and outer side of said hubsection is supported by a bearing, and said pressure regulatingmechanism is situated in inner side of said hub section.
 3. A beltdriven continuously variable transmission defined in claim 1, whereinsaid sheave is a stationary sheave of said primary pulley.
 4. A beltdriven continuously variable transmission defined in claim 1, whereinsaid pressure regulating mechanism is a pressure regulating cammechanism which has an wave-shaped end surface and generates axial forceby either positive or negative torque transmission.
 5. A belt drivencontinuously variable transmission of defined in claim 1, wherein saidbelt driven continuously variable transmission which is used for anautomatic continuous variable transmission where connecting a secondaryshaft of said belt driven continuously variable transmission to a firstrotating element of a planetary gear device; connecting a third rotatingelement of said planetary gear device, through a clutch, to an inputshaft transmitting power to a primary shaft of said continuouslyvariable transmission; furthermore connecting a second rotating elementof said planetary gear device to an output section; whereby powertransmission is conducted exclusively through said belt drivencontinuously variable transmission under the condition that saidplanetary gear device works as a reduction mechanism by releasing saidclutch and restraining said third rotating element; by engaging saidclutch, said planetary gear mechanism works as a split drive mechanismto combine torque transmitted through said belt driven continuouslyvariable transmission and torque transmitted from said input shaft tosaid third rotating element.